(i) Technical Field
The present invention relates to an image forming apparatus, a non-transitory computer readable medium, and an image forming method.
(ii) Related Art
In an inkjet printer, nozzle clogging occurs owing to drying and increase in viscosity of ink disused for an extended time. Therefore, preliminary discharge is performed which discharges ink independently of printing to clear the nozzle clogging.
An inkjet printer mostly for personal or home use performs printing while moving a print head, and thus is capable of performing the preliminary discharge in an area where a recording medium is absent. Meanwhile, a large single-pass printer with a line head, particularly a large business-use inkjet printer using a rolled sheet, performs printing on a sheet uninterruptedly without feeding any other blank sheet during the printing, and thus is incapable of performing the preliminary discharge in an area where a recording medium is absent, and needs perform the preliminary discharge on the recording medium.
Therefore, there have been proposed line dropping of preliminarily discharging ink in lines onto a head portion of a sheet and random dropping of preliminarily discharging ink at random over the entire surface of a sheet, which are performed in certain sheet printing units.
FIGS. 11A and 11B schematically illustrate the line dropping and the random dropping. FIG. 11A illustrates line drops 102 preliminarily discharged in lines onto a head portion of a sheet 100. If cyan (C), magenta (M), yellow (Y), and black (K) are used as process colors, the line drops 102 are preliminarily discharged in lines for the respective process colors. Meanwhile, FIG. 11B illustrates random drops 104 preliminarily discharged at random over the entire surface of a sheet In both of the drawings, different hatching patterns indicate different colors.